update branch diff with improved logic, logging, and help

Author: zbhavyai

src/git_branch_diff.sh

@@ -1,44 +1,104 @@
 #!/usr/bin/env bash
 set -euo pipefail
 
+CURR_SCRIPT=$(readlink -f "$0")
+CURR_SCRIPT_PATH=$(dirname "${CURR_SCRIPT}")
+
+# help
+# -------------------------------------------------------------------------------------
+function help() {
+    echo
+    echo "Generate diff between current branch and a base branch."
+    echo
+    echo "Usage:"
+    echo "    ${0} [OPTION]"
+    echo
+    echo "Options:"
+    echo "    -b <branch>    generate diff against base branch (default: main)"
+    echo "    -h             show this help message"
+    echo
+    echo "Examples:"
+    echo "    ${0}"
+    echo "    ${0} -b main"
+    echo
+}
+
+# logging
+# -------------------------------------------------------------------------------------
+function logger() {
+    local LEVEL=$1
+    shift
+    printf "%s [%5s] %s\n" "$(date +'%F %T.%3N')" "${LEVEL}" "$*"
+}
+log_info() { logger INFO "$@"; }
+log_warn() { logger WARN "$@"; }
+log_error() { logger ERROR "$@" 1>&2; }
+
+# update branches
+# -------------------------------------------------------------------------------------
 function update_branches() {
     git fetch origin >/dev/null 2>&1 || true
 }
 
-function get_branch_diff() {
-    local COMPARE_WITH_BRANCH="${1}"
-    local BRANCH_TO_COMPARE="HEAD"
-    local FILES
+# generate branch diff
+# -------------------------------------------------------------------------------------
+function generate_branch_diff() {
+    local BASE_BRANCH=$1
+    local CURRENT_BRANCH
 
-    echo "Running branch diff"
-    echo "Comparing: ${BRANCH_TO_COMPARE}"
-    echo "with     : ${COMPARE_WITH_BRANCH}"
-    echo
+    CURRENT_BRANCH=$(git rev-parse --abbrev-ref HEAD)
+
+    log_info "Current branch : ${CURRENT_BRANCH}"
+    log_info "Base branch    : ${BASE_BRANCH}"
+
+    if ! git show-ref --verify --quiet "refs/heads/${BASE_BRANCH}" &&
+        ! git show-ref --verify --quiet "refs/remotes/origin/${BASE_BRANCH}"; then
+        log_error "Base branch '${BASE_BRANCH}' does not exist"
+        exit 1
+    fi
 
     update_branches
 
-    FILES=$(git diff --name-only "${BRANCH_TO_COMPARE}...${COMPARE_WITH_BRANCH}")
+    local FILES
+    FILES=$(git --no-pager diff --name-status "${BASE_BRANCH}...HEAD")
 
-    if [ -z "${FILES}" ]; then
-        echo "No changes detected between branches."
+    if [[ -z "${FILES}" ]]; then
+        log_info "No changes detected."
         return
     fi
 
-    echo "Files changed..."
+    echo
+    log_info "Files changed:"
     echo "${FILES}"
     echo
 
-    echo "Generating branch diff..."
-    git diff --unified=5 "${BRANCH_TO_COMPARE}...${COMPARE_WITH_BRANCH}"
+    log_info "Generating diff..."
+    git --no-pager diff --unified=5 "${BASE_BRANCH}...HEAD"
 }
 
-function main() {
-    if [[ $# -lt 1 ]]; then
-        echo "Usage: $0 BRANCH_TO_COMPARE_WITH"
-        exit 1
-    fi
+# driver code
+# -------------------------------------------------------------------------------------
+BASE_BRANCH="main"
 
-    get_branch_diff "$@"
-}
+while getopts ":hb:" opt; do
+    case "${opt}" in
+    h)
+        help
+        exit 0
+        ;;
+    b)
+        BASE_BRANCH="${OPTARG}"
+        ;;
+    \?)
+        log_error "Invalid option"
+        help
+        exit 1
+        ;;
+    :)
+        log_error "Option -${OPTARG} requires an argument"
+        exit 1
+        ;;
+    esac
+done
 
-main "$@"
+generate_branch_diff "${BASE_BRANCH}"